Digital-to-analog converters, as the name implies, convert a digital input signal to a corresponding analog output signal. In transition of the analog output signal from an old value to a new value in response to a change in the digital input signal, digital-to-analog converters generate a spike or distortion in the output signal before the signal settles to its new value. This distortion is of major concern in circumstances where the analog signal is to be displayed or otherwise sensed. For example, in a digital oscilloscope, a waveform may be stored digitally in memory and then displayed in the analog form at some later time. The digital signal values representing the waveforms are converted to discrete analog dots on a display. To produce the appearance of a continuous waveform, a vector filter generates a transition signal that is displayed to connect one dot to the next. However, the output distortion is also displayed, giving a misleading appearance to the reproduced waveform.
Attempts in the past to remove this distortion from the reproduced waveform have focused on utilizing improved digital-to-analog converter technology to minimize the signal spike. Although new technology has lead to some improvement, it has not totally removed the distortion, especially in light of the higher frequency signals applied to the digital-to-analog converters in advanced instrumentation. Moreover, the high performance circuitry that is required has a much higher cost than standard circuit devices.